On 2021-03-04 00:46, Justin He wrote:
Hi Marc
-----Original Message-----
From: Will Deacon <[email protected]>
Sent: Thursday, March 4, 2021 5:13 AM
To: Marc Zyngier <[email protected]>
Cc: Justin He <[email protected]>; [email protected]; James
Morse <[email protected]>; Julien Thierry
<[email protected]>;
Suzuki Poulose <[email protected]>; Catalin Marinas
<[email protected]>; Gavin Shan <[email protected]>; Yanan Wang
<[email protected]>; Quentin Perret <[email protected]>;
linux-arm-
[email protected]; [email protected]
Subject: Re: [PATCH] KVM: arm64: Fix unaligned addr case in mmu
walking
On Wed, Mar 03, 2021 at 07:07:37PM +0000, Marc Zyngier wrote:
> From e0524b41a71e0f17d6dc8f197e421e677d584e72 Mon Sep 17 00:00:00 2001
> From: Jia He <[email protected]>
> Date: Wed, 3 Mar 2021 10:42:25 +0800
> Subject: [PATCH] KVM: arm64: Fix range alignment when walking page tables
>
> When walking the page tables at a given level, and if the start
> address for the range isn't aligned for that level, we propagate
> the misalignment on each iteration at that level.
>
> This results in the walker ignoring a number of entries (depending
> on the original misalignment) on each subsequent iteration.
>
> Properly aligning the address at the before the next iteration
"at the before the next" ???
> addresses the issue.
>
> Cc: [email protected]
> Reported-by: Howard Zhang <[email protected]>
> Signed-off-by: Jia He <[email protected]>
> Fixes: b1e57de62cfb ("KVM: arm64: Add stand-alone page-table walker
infrastructure")
> [maz: rewrite commit message]
> Signed-off-by: Marc Zyngier <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> ---
> arch/arm64/kvm/hyp/pgtable.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 4d177ce1d536..124cd2f93020 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -223,7 +223,7 @@ static inline int __kvm_pgtable_visit(struct
kvm_pgtable_walk_data *data,
> goto out;
>
> if (!table) {
> - data->addr += kvm_granule_size(level);
> + data->addr = ALIGN(data->addr, kvm_granule_size(level));
What if previous data->addr is already aligned with
kvm_granule_size(level)?
Hence a deadloop? Am I missing anything else?
Indeed, well spotted. I'll revert to your original suggestion
if everybody agrees...
Thanks,
M.
--
Jazz is not dead. It just smells funny...
